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From "Runping Qi (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-210) Namenode not able to accept connections
Date Thu, 11 May 2006 18:07:07 GMT
    [ http://issues.apache.org/jira/browse/HADOOP-210?page=comments#action_12379117 ] 

Runping Qi commented on HADOOP-210:
-----------------------------------


Reducing stack size may relieve the problem temporally, but will not solve the problem completely.
It seems to me that the problem is due to the fact that a thread is created per RPC connection.
A better solution is to use a thread pool and a connection queue. This way, it is easier to
manage the resource limits.



> Namenode not able to accept connections
> ---------------------------------------
>
>          Key: HADOOP-210
>          URL: http://issues.apache.org/jira/browse/HADOOP-210
>      Project: Hadoop
>         Type: Bug

>   Components: dfs
>  Environment: linux
>     Reporter: Mahadev konar
>     Assignee: Mahadev konar

>
> I am running owen's random writer on a 627 node cluster (writing 10GB/node).  After running
for a while (map 12% reduce 1%) I get the following error on the Namenode:
> Exception in thread "Server listener on port 60000" java.lang.OutOfMemoryError: unable
to create new native thread
>         at java.lang.Thread.start0(Native Method)
>         at java.lang.Thread.start(Thread.java:574)
>         at org.apache.hadoop.ipc.Server$Listener.run(Server.java:105)
> After this, the namenode does not seem to be accepting connections from any of the clients.
All the DFSClient calls get timeout. Here is a trace for one of them:
> java.net.SocketTimeoutException: timed out waiting for rpc response
> 	at org.apache.hadoop.ipc.Client.call(Client.java:305)
> 	at org.apache.hadoop.ipc.RPC$Invoker.invoke(RPC.java:149)
> 	at org.apache.hadoop.dfs.$Proxy1.open(Unknown Source)
> 	at org.apache.hadoop.dfs.DFSClient$DFSInputStream.openInfo(DFSClient.java:419)
> 	at org.apache.hadoop.dfs.DFSClient$DFSInputStream.(DFSClient.java:406)
> 	at org.apache.hadoop.dfs.DFSClient.open(DFSClient.java:171)
> 	at org.apache.hadoop.dfs.DistributedFileSystem.openRaw(DistributedFileSystem.java:78)
> 	at org.apache.hadoop.fs.FSDataInputStream$Checker.(FSDataInputStream.java:46)
> 	at org.apache.hadoop.fs.FSDataInputStream.(FSDataInputStream.java:228)
> 	at org.apache.hadoop.fs.FileSystem.open(FileSystem.java:157)
> 	at org.apache.hadoop.mapred.TextInputFormat.getRecordReader(TextInputFormat.java:43)
> 	at org.apache.hadoop.mapred.MapTask.run(MapTask.java:105)
> 	at org.apache.hadoop.mapred.TaskTracker$Child.main(TaskTracker.java:785).
> The namenode then has around 1% CPU utilization at this time (after the outofmemory exception
has been thrown). I have profiled the NameNode and it seems to be using around a maixmum heap
size of 57MB (which is not much). So, heap size does not seem to be a problem. It might be
happening due to lack of Stack space? Any pointers?

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